1. Field of the Invention
The present invention relates to an apparatus and a method for verifying the validity of an extensible markup language (XML) document, a well-known standard electronic document, by using a schema/document type definition (DTD) data structure describing a grammar of the XML document, and more particularly, to an apparatus and a method for solving the problem of a parser which cannot support the verification of the validity of an XML document using a general schema/DTD data structure in an embedded device having a relatively low-performance processor and a small memory due to restrictions regarding the specifications of the embedded device.
2. Description of the Related Art
In the prior art, an XML parser having a validator used to verify the validity of an XML document is written using an external entity, in an XML application using the XML document. The validator reads a schema/DTD from an external source, generates the structure of data on a grammar defined using the schema/DTD, and checks an error in the XML document using the defined grammar. However, the XML application operating in an embedded device, e.g., a personal digital assistant (PDA), a portable phone, or the like, has limitations in verifying the validity of the XML document. Most embedded systems support an XML parser that does not support the verification of the validity of an XML document or an XML parser, a portion of which is extended to verify only a limited schema or grammar of a DTD, in order to reduce load due to a process of verifying the XML document using a schema or a DTD. Due to this, a special validating parser is realized to perceive only a schema/DTD necessary for each system. Thus, the special validating parser cannot be used in other systems.
Also, if a schema/DTD publisher publishing a schema/DTD used as an external entity in an XML document realizes new grammar, an XML document, which uses an existing schema/DTD and has no errors, is not validated any more. Thus, the XML document using the schema/DTD published as the external entity has to be newly constituted with changes in a schema or grammar of a DTD.